Develop Reference

I cannot Import bytedeco's JavaCV into my project on IntelliJ

I downloaded bytedeco's JavaCV from github and have included it into my dependencies for my IntelliJ project.
I then read through the documentation and the readme file and then figure out what I think were the proper import statements.
I have tried "import org.bytedeco.javacv.*;" from what I found in the package in the package names.
That did not work, IntelliJ could not resolve symbol "bytedeco". This happened even in the JavaCV classes that are a part of the org.bytedeco.javacv package did not resolve the import statements. I then went onto stack overflow to look for anyone who had the same problem or could solve my problem. I couldn't find any useful information at all about what is wrong.
I found this very confusing and could not find any other information onto why this is happening. This is my first project, I do not know if this is a limitation with IntelliJ or that I am missing some other package that isn't part of JavaCV or some other problem I do not yet know of.

That's right the correct package name should be org.bytedeco.opencv.global.opencv_core.*.
Here is a sample code taken from the GitHub:
import org.bytedeco.opencv.opencv_core.*;
import org.bytedeco.opencv.opencv_imgproc.*;
import static org.bytedeco.opencv.global.opencv_core.*;
import static org.bytedeco.opencv.global.opencv_imgproc.*;
import static org.bytedeco.opencv.global.opencv_imgcodecs.*;
public class Smoother {
public static void smooth(String filename) {
Mat image = imread(filename);
if (image != null) {
GaussianBlur(image, image, new Size(3, 3), 0);
imwrite(filename, image);
}
}
}
You may find the sample code on the official GitHub project site helpful for a fast start:
https://github.com/bytedeco/javacv/tree/master/samples
https://github.com/bytedeco/javacv#manual-installation

How to load video in OpenCV (Java)

I'm trying to load a video file in OpenCV Java, and have narrowed down my issue to the following code:
import org.opencv.core.Core;
import org.opencv.videoio.VideoCapture;
public class OpenCVTest {
public static void main(String[] args) {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
System.loadLibrary("opencv_videoio_ffmpeg455_64");
VideoCapture capture = new VideoCapture("myVideoFile.avi");
System.out.println(capture.isOpened());
}
}
Of course, this always prints out "false". Accessing my computer's camera with new VideoCapture(0) works fine. After scouring the internet, I'm thoroughly confused as to why loading a video won't work. I followed guides that suggested I needed to add "opencv_videoio_ffmpeg455_64.dll" to my path variable and call System.loadLibrary. I'm new to this, and to be honest, I don't understand what loadLibrary does, or what could be wrong with my setup and code. Any ideas? Thanks in advance.

Here is the answer from similar problem
load the ffmpeg library System.loadLibrary("opencv_ffmpeg300_64");
Open the file:
VideoCapture vC = new VideoCapture("res/video.mp4");
Copy opencv_ffmpeg300_64.dll from opencv\build\x64\vc11\bin to
opencv\build\java\x64
Please note that 64 and .dll may differ from an OS to another, those are for Windows x64

As it turns out, I was using the wrong file path. I (wrongly) assumed that new VideoCapture("my file") would search for "my file" in the directory where the compiled .class files are placed, when in fact it searches in the project root directory. There is no need to call System.loadLibrary("opencv_videoio_ffmpeg455_64");

Can't get OpenCV to work with Java+Maven+IntelliJ

I've seen lots of people asking similar questions to mine but their solutions aren't working for me. Here's what I've got:
I downloaded the latest OpenCV for Windows (2.4.9). I extracted this to C:\opencv-249
I then created a new Maven 3 project in IntelliJ. This works fine and I can run the compile/package goals, etc. I can execute and debug my program. This is all good.
Next, I tried to pull OpenCV into my test app and ended up with the following code:
package com.foo.OpenCVTest;
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.CvType;
/**
* Created by rick on 5/7/2014.
*/
public class RobotCntrl {
static{ System.loadLibrary(Core.NATIVE_LIBRARY_NAME); }
static public void main(String args[]) {
System.out.println("In main!");
System.out.println("Core Lib: " + Core.NATIVE_LIBRARY_NAME);
Mat m = Mat.eye(3, 3, CvType.CV_8UC1);
System.out.println("m = " + m.dump());
}
}
I then added the local OpenCV to my pom.xml:
<dependency>
<groupId>org.opencv</groupId>
<artifactId>opencv</artifactId>
<version>2.4.9</version>
<systemPath>${java.home}/../../../../opencv-249/build/java/opencv-249.jar</systemPath>
<scope>system</scope>
</dependency>
And I added OpenCV as a project library:
And I modified the IntelliJ VM Options (Edit Configurations) to update the java.library.path to point to the OpenCV dlls:
When I run the application appears to load the opencv_java249.dll library just fine (it doesn't complain), but for the line:
Mat m = Mat.eye(3, 3, CvType.CV_8UC1);
It bombs out complaining that it can't find the underlying n_eye() native function:
In main!
Exception in thread "main" java.lang.UnsatisfiedLinkError: org.opencv.core.Mat.n_eye(III)J
Core Lib: opencv_java249
at org.opencv.core.Mat.n_eye(Native Method)
at org.opencv.core.Mat.eye(Mat.java:1467)
at com.aether.Robots.RobotCntrl.main(RobotCntrl.java:25)
Process finished with exit code 1
I'm at a loss now. It's loading the wrapper library but it can't call the dependent functions. For the previous questions on similar issues, it tends to be resolved when people update their java.library.path variable, but mine seems correct:
-Djava.library.path=C:\opencv-249\build\x64\vc10\bin;C:\opencv-249\build\java\x64
or people forget to call System.loadLibrary(), but that call is succeeding (as far as I can tell) for me.
Any ideas?

Using GraphVIZ Native library from Java

I am trying to use graphviz native library from java.I am able to compile the program in Eclipse. But getting exception:
Exception in thread "main" java.lang.UnsatisfiedLinkError: no gv in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1681)
at java.lang.Runtime.loadLibrary0(Runtime.java:840)
at java.lang.System.loadLibrary(System.java:1047)
at org.graphviz.test.Test.<clinit>(Test.java:12)
Could not find the main class: org.graphviz.test.Test. Program will exit.
Here is my code(copied from somewhere of course):
package org.graphviz.test;
import org.graphviz.internal.SWIGTYPE_p_Agedge_t;
import org.graphviz.internal.SWIGTYPE_p_Agnode_t;
import org.graphviz.internal.SWIGTYPE_p_Agraph_t;
import org.graphviz.internal.gv;
public class Test {
static {
System.loadLibrary("gv");
}
public static void main(String[] args) {
SWIGTYPE_p_Agraph_t g, sg;
SWIGTYPE_p_Agnode_t n, m;
SWIGTYPE_p_Agedge_t e;
g = gv.digraph("G");
System.out.println(gv.setv(g,"aaa","xxx"));
System.out.println(gv.getv(g,"aaa"));
sg = gv.graph(g,"SG");
n = gv.node(g,"hello");
System.out.println(gv.getv(n,"label"));
System.out.println(gv.setv(n,"aaa","xxx"));
System.out.println(gv.getv(n,"aaa"));
m = gv.node(g,"world");
System.out.println(gv.getv(m,"aaa"));
e = gv.edge(n,m);
System.out.println(gv.setv(e,"aaa","xxx"));
System.out.println(gv.getv(e,"aaa"));
gv.rm(e);
gv.rm(n);
gv.rm(m);
gv.rm(g);
g = gv.readstring("digraph G {a->b}");
gv.rm(g);
g = gv.read("hello.gv");
gv.layout(g,"dot");
gv.render(g,"png","hello.png");
gv.rm(g);
}
}
I have pointed the library correctly, but at runtime getting UnsatisfiedLinkError. Any one ever tried using the graphviz native library?Please let me know how to configure JNI.

I believe you're problem is that you are trying to import from gv, but you aren't specifying what you want to import. It's kind of like if you were to just write ---
import org.graphviz.internal;
Instead, try importing a specific library from the gv library. For example, if you want a directed graph, you would probably do something like this ---
import org.graphviz.internal.gv.digraph;
Take a look at the following document and see if it helps at all. It might give you a better idea of where gv comes from and how you can import the methods associated with it.
http://www.graphviz.org/pdf/gv.3java.pdf

Get graphviz-java
Make sure you have graphviz-java installed. For MacPorts this should work like this:
sudo port install graphviz +java
This actually failed for me on the first try and complained about swig-java, this fixed it:
sudo port install swig-java
sudo port install graphviz +java
Now the library is installed under /opt/local/lib/graphviz/java for me, search for libgv.jnilib if you don't find it there.
Setup class path
I compiled in Eclipse, for that I added /opt/local/lib/graphviz/java to the build path as an external class folder.
Compile
This is a simple example that writes an image. Note that System.loadLibrary("gv") must happen before calling anything in graphviz.
import org.graphviz.SWIGTYPE_p_Agedge_t;
import org.graphviz.SWIGTYPE_p_Agnode_t;
import org.graphviz.SWIGTYPE_p_Agraph_t;
import org.graphviz.gv;
public class Main {
static {
System.loadLibrary("gv");
}
public static void main(String[] args) {
SWIGTYPE_p_Agraph_t g = gv.digraph("G");
SWIGTYPE_p_Agnode_t n = gv.node(g, "hello");
SWIGTYPE_p_Agnode_t m = gv.node(g, "world");
SWIGTYPE_p_Agedge_t e = gv.edge(n, m);
gv.layout(g, "dot");
gv.render(g, "png", "hello.png");
}
}
Run
Run with java.library.path=/opt/local/lib/graphviz/java, e.g. -Djava.library.path=/opt/local/lib/graphviz/java as VM arguments in an Eclipse run configuration.

JavaCV/OpenCV: cvLoadImage not working

I installed the JavaCV/OpenCV libraries, and I'm having a problem with the basic example code.
According to several examples that I have looked at, this code should load an image:
IplImage image = cvLoadImage("C:\\img.jpg");
But, when I run that I get a "cannot find symbol" error.
Since this is my first time using it, I'm not sure if I messed the install up or not.
According to the newest JavaCV readme, I do have the correct version of OpenCV. I also have all the JavaCV jar files imported. As far as I can tell, I also have all the paths set correctly too.
Anyone know what the problem is?
Edit:
Full code:
import com.googlecode.javacv.CanvasFrame;
import com.googlecode.javacv.cpp.opencv_core.IplImage;
import java.io.File;
public class demo {
public static void main(String[] args)
{
IplImage image = cvLoadImage("C:\\img.jpg");
final CanvasFrame canvas = new CanvasFrame("Demo");
canvas.showImage(image);
canvas.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
}
}
Error when I try to run it:
Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous sym type: cvLoadImage
at javacv.demo.main(demo.java:17)
Java Result: 1
Seems like it is claiming cvLoadImage doesn't take a string as an argument.

A walk around that i find for you is to load the image by ImageIO and passe it later to IplImage
e.g.:
BufferedImage img = ImageIO.read(new File("C:\\img.jpg") );
IplImage origImg = IplImage.createFrom(img);

This solved my problem: import static org.bytedeco.javacpp.opencv_imgcodecs.*;

You have to add this import statement:
import static org.bytedeco.javacpp.opencv_imgcodecs.cvLoadImage;
This is required so that the static method cvLoadImage can be used without using the class name.

You have to import com.googlecode.javacv.cpp.opencv_highgui.*;

With javacv 0,9 you have to import static org.bytedeco.javacpp.opencv_highgui.*;

I got the same error then, i imported the following package, problem solved.
import static com.googlecode.javacv.cpp.opencv_highgui.*;

This might be old but for those who stumbled upon this problem like me just now,
here is how I solved it and why:
First OP's error: Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous sym type: cvLoadImage at javacv.demo.main(demo.java:17)
This indicates that the compiler cannot find the cvLoadImage method that you are trying to call.
cvLoadImage is a static method under JavaCPP.
Specifically it is a static method under opencv_imgcodecs class.
To solve this issue one must first specify the import of the opencv_imgcodecs class.
This can be done by adding the import:
import static org.bytedeco.javacpp.opencv_imgcodecs.cvLoadImage;
This in turn would result for the opencv_imgcodecs class to be usable within your class along with its static methods and other functions.
I hope this helps.

Got the same problem recently.
if you are using javacv-0.10 (more recent at the moment), import manually this one:
import static org.bytedeco.javacpp.opencv_highgui.*;
but the source of JRE of the project should be higher than 1.5

In my case, the problem happened when the squeegee in debug mode.
Try to run in normal mode.